U.S. Pat. No. 3,821,821 shows an adjustable foot area of the hospital bed which has a pair of braces 86 with notched dogleg sections. These dogleg sections each slide in a loop retainer 90. This construction has certain problems in that the braces bind in the loop retainer, particularly when the adjustable foot section of the bed is unevenly loaded. This may occur when the patient is not lying directly in the middle of the bed or stretcher when an adjustment to the foot section is made.
Another U.S. Pat. No. 3,972,081 utilizes a series of holes 332, 333 in a substructure of the stretcher or bed. Hinged brace 327 has a tab 329 that fits into these holes. Here again the problem of slight lateral cocking of the adjustable mattress support can cause the braces on each side of the stretcher to bind at their particular openings during the adjustment procedure. Also, with the construction described in this patent, it would be easy to get the tabs in holes that were not laterally corresponding to each other. This would cause a warping or cocking of the stretcher's foot section.
This warping is also apparent in wooden lawn chairs that have been available for many years. Such lawn chairs have an adjustable back support with a pair of braces similar to those shown at 68 in U.S. Pat. No. 3,821,821. The chair has a base section similar to 18 that has a series of notches along its upper edge. A transverse wooden dowel between the lawn chair braces 68 engages these various notches to adjust the back of the lawn chair to various angular positions. The big problem is that the dowel and braces twist and the dowel engages notches that are not directly opposed to each other on the two base rails. This causes cocking of the lawn chair back.